Magnetically Hard Fe3Se4 Embedded in Bi2Se3 Topological Insulator Thin Films Grown by Molecular Beam Epitaxy

Vasconcelos, Hugo Menezes do Nascimento; Eddrief, M.; Zheng, Y.; Demaille, Dominique; Hidki, S.; Fonda, Emiliano; Новикова, А. А.; Fujii, Jun; Torelli, Piero; Salles, B. Rache; Vobornik, I.; Panaccione, G.; Oliveira, A. J. A. de; Marangolo, M.; Vidal, Franck

doi:10.1021/acsnano.5b06430

Cited by 11 publications

(9 citation statements)

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“…The Bi:Se chemical ratio was found to be 1.5, thus indicating a correct stoichiometry of the Bi 2 Se 3 thin films. Interestingly, even in the case of a slight Se-deficiency (for instance tuned by varying the target-to-substrate distance, as previously discussed), the topological properties (i.e., a single Dirac cone with well-defined spin-texturing) are not lost, while the Dirac cone is rigidly shifted to higher binding energies as already reported for thin films 4,6 and also for single crystals. [28][29][30] Spin and angular resolved photoemission experiments were performed on in-situ transferred as-grown Bi 2 Se 3 thin films at a temperature of 77 K and with a synchrotron radiation spot of about 100 Â 50 lm.…”

supporting

confidence: 67%

“…1-3 Even though they are insulating in the bulk, they show a metallic surface state characterized by a unique spin texture, as unambiguously demonstrated by spin-resolved angular resolved photoemission spectroscopy (ARPES) experiments. [4][5][6][7] Furthermore, these states are topologically protected against scattering driven by strong spin-orbit interactions, thus being attractive as functional materials for spintronic applications. 8,9 However, for both fundamental studies and electronic applications, high-quality singlecrystalline Bi 2 Se 3 thin films, exhibiting topologically protected surface states, are therefore necessary.…”

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confidence: 99%

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Structural and electronic properties of Bi2Se3 topological insulator thin films grown by pulsed laser deposition

Orgiani

Bigi

Das

et al. 2017

Applied Physics Letters

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We report on epitaxial growth of Bi2Se3 topological insulator thin films by Pulsed Laser Deposition (PLD). X-ray diffraction investigation confirms that Bi2Se3 with a single (001)-orientation can be obtained on several substrates in a narrow (i.e., 20 °C) range of deposition temperatures and at high deposition pressure (i.e., 0.1 mbar). However, only films grown on (001)-Al2O3 substrates show an almost-unique in-plane orientation. In-situ spin-resolved angular resolved photoemission spectroscopy experiments, performed at the NFFA-APE facility of IOM-CNR and Elettra (Trieste), show a single Dirac cone with the Dirac point at E B ∼ 0.38 eV located in the center of the Brillouin zone and the spin polarization of the topological surface states. These results demonstrate that the topological surface state can be obtained in PLD-grown Bi2Se3 thin films

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confidence: 67%

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confidence: 99%

Structural and electronic properties of Bi2Se3 topological insulator thin films grown by pulsed laser deposition

Orgiani

Bigi

Das

et al. 2017

Applied Physics Letters

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“…It is not necessarily that Sr atoms are randomly distributed in the lattice. We can't exclude formation of metal-rich nanoclusters [29,41], flat inclusions [42], segregation [43], or even well arranged blocks [44]. However, in XRD similar imperfections are usually manifested just as a broadening of the reflections, while detection of the specific Sr-enriched structures by means of TEM is rather challenging.…”

Section: Discussionmentioning

confidence: 99%

Effect of Sr doping on structure, morphology, and transport properties of Bi2Se3 epitaxial thin films

Volosheniuk

Selivanov

Bryzgalov

et al. 2019

Journal of Applied Physics

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We report molecular beam epitaxy growth of Sr-doped Bi 2 Se 3 films on (111) BaF 2 substrate, aimed to realize unusual superconducting properties inherent to Sr x Bi 2 Se 3 single crystals. Despite wide range of the compositions, we do not achieve superconductivity. To explore the reason for that we study structural, morphological and electronic properties of the films and compare them to the corresponding properties of the single crystals. The dependence of the c-lattice constant in the films on Sr content appears to be more than an order of magnitude stronger than in the crystals. Correspondingly, all other properties also differ substantially, indicating that Sr atoms get different positions in lattices. We argue that these structural discrepancies come from essential differences in growth conditions. Our research calls for more detailed structural studies and novel growth approaches for design of superconducting Sr x Bi 2 Se 3 thin films.PACS numbers:

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“…For x = 0.20, the number of such precipitates increases. An additional x-ray diffraction peak appears at around 2 angle of 16.1°, which we assigned to Fe3Se4 (001) [29]. Based on the results of analyses presented above, we evaluate the solubility limit of Fe as approximately x = 0.1.…”

Section: Structural Analysismentioning

confidence: 99%

“…To materialize the QAH phase in TIs, the surface electronic states should be modified by the exchange gap owing to some mechanisms (1) coupling between surface state and ferromagnetically aligned spins of transition metal impurities [15][16][17] or aligned spins by external magnetic field in the antiferromagnetic topological insulator [18,19], (2) proximity coupling effect with adjacent magnetic moment [20][21][22], or (3) band crossing driven by a Zeeman splitting [17,23]. To date, experimental observations of the QAH effect have been accomplished for Cr-doped or V-doped (Bi,Sb)2Te3 (BST) 3D-TI films, where a perpendicular spontaneous magnetization develops below the Curie temperature (type (1)) [15,16,[24][25][26][27][28], and for a proximitized (Bi,Sb)2Te3/ferromagnetic insulator heterostructure (type (2)) [29]. In contrast, type (3) of QAH has not been observed in paramagnetic (Bi,Sb)2Se3-based TIs, whereas the quantization of the Hall resistance is accomplished by the application of a magnetic field to a 4 quintuple layer of Cr-doped (Bi,Sb)2Te3 [30], Ti-doped (Bi,In)3Te2 [31], and MnBi2Te4 [18,19].…”

Section: Introductionmentioning

confidence: 99%

Magnetic-field-induced topological phase transition in Fe-doped (Bi,Sb)2Se3 heterostructures

Satake

Shiogai

Mazur

et al. 2020

Phys. Rev. Materials

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Three-dimensional topological insulators (3D-TIs) possess a specific topological order of electronic bands, resulting in gapless surface states via bulk-edge correspondence.Exotic phenomena have been realized in ferromagnetic TIs, such as the quantum anomalous Hall (QAH) effect with a chiral edge conduction and a quantized value of the Hall resistance Ryx. Here, we report on the emergence of distinct topological phases in paramagnetic Fe-doped (Bi,Sb)2Se3 heterostructures with varying structure architecture, doping, and magnetic and electric fields. Starting from a 3D-TI, a two-dimensional insulator appears at layer thicknesses below a critical value, which turns into an Anderson insulator for Fe concentrations sufficiently large to produce localization by magnetic disorder. With applying a magnetic field, a topological transition from the Anderson insulator to the QAH state occurs, which is driven by the formation of an exchange gap owing to a giant Zeeman splitting and reduced magnetic disorder. Topological phase diagram of (Bi,Sb)2Se3 allows exploration of intricate interplay of topological protection, magnetic disorder, and exchange splitting.The Zeeman exceeding hy forms a non-trivial exchange gap with one-dimensional chiraledge channel as shown in Figs. 1(e) and 1(f), with gap size proportional to the magnetic field. In Fig. 1(f), red (blue) thick curve shows the chiral edge mode at one (the other) edge. With a minor contribution of the ordinary Hall effect under magnetic field owing to Fermi energy (EF) locating in the gap, the magnetic-field-induced anomalous Hall effect plays a critical role for the quantization of the Hall conductivity. This study demonstrates the presence of TPTs between 3D-TI, a two-dimensional (2D) insulator, and QAH phases in paramagnetic Fe-doped Bi2Se3-based heterostructures by controlling Fe doping and layer thickness and by application of external magnetic and electric fields. The tetradymite compound Bi2Se3 is a representative 3D-TI, in which a large bulk band gap (approximately 300 meV) hosts gapless surface states [35]. Using angleresolved photoemission spectroscopy (ARPES) of surface states, 50 meV gap formation was detected in paramagnetic Fe-doped bulk Bi2Se3; it was assigned to breakage of the time-reversal symmetry by exchange interactions [36]. Effects of magnetic impurities upon topological surface states were also studied by in-situ deposition of Fe atoms [37-39]. It was found that Fe acts as donor [37,38] if deposited at room temperature but as an acceptor if deposited at 8 K [38]. A question on whether the presence of a Fe surface layer 6 opens a gap or not in the topological states was also examined experimentally and theoretically [37-39].According to one theoretical proposal, Fe-doped Bi2Se3-based heterostructures are a preferred platform for observing the emergence of QAH phase [17]. Nevertheless, no QAH effect has yet been observed in magnetically doped Bi2Se3-based films, probably because of the absence or weakness of the ferromagnetic ordering, and associat...

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Magnetically Hard Fe₃Se₄ Embedded in Bi₂Se₃ Topological Insulator Thin Films Grown by Molecular Beam Epitaxy

Cited by 11 publications

References 50 publications

Structural and electronic properties of Bi2Se3 topological insulator thin films grown by pulsed laser deposition

Structural and electronic properties of Bi2Se3 topological insulator thin films grown by pulsed laser deposition

Effect of Sr doping on structure, morphology, and transport properties of Bi2Se3 epitaxial thin films

Magnetic-field-induced topological phase transition in Fe-doped (Bi,Sb)2Se3 heterostructures

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